Cam Duc, Vietnam Analytical Method   Method: The indicator organisms used in this study were salmonella typhymurium phages 28B and Ascaris suum eggs. Lab assays were modified and introduced by the Swedish Institute for Infectious Disease Control. Phages were mixed with faecal material in a concentration of 1.108 pfu/g [plaque forming units per gram]. Eggs were put in "tea bags" made of polyamide cloth, with 104 eggs/bag. All were put into stainless steel cylinders, 11 - 14 cm in diameter, in which were drilled a number of 2 mm diameter holes. These cylinders were placed in 12 toilets processing chambers or toilet buckets, in the middle, for a period of two weeks to determine the survival time of phages and As. Eggs. Other factors monitored included moisture content, temperature, pH, and nitrogen content (total and inorganic loadings).